Vacuum distillation procedure



March 7, 1944. Q Q HlCKMAN 2,343,666

VACUUM DISTILLATION PROCEDURE Filed July 26, 1941 DEGASSED OIL IN I2 TOVACUUM PUMP FILM OR SPRAY DISTILLATE I RESIDUE F|G .4 v

- 68 F 66 FIRE.

CONDENSING SURFACE RESIDU! KENNETH an. HIEKMAN .JEIHN 1:. HEBKERINVENTORS A TTOR NE Y5 Patented Mar. 7, 1914 VACUUM DI SI' ILLATIONPROCEDURE Kenneth C. D. Hickman and-John 0. Becker,-

Rocheater, N. Y., aasignors to Distillation Prodnets, Ina, Rochester, N.Y., a corporation of Delaware Application Jul! zs. 1041. Serial s. mazes'cmm. (Cl. 202-52) This invention relates to improved vacuumdistiliation process, particularly of the type wherein the substancebeing distilled and the condensing surface are separated bysubstantially unobstructed space.

. Substances which are ordinarily distilled under vacuum conditions arerelatively non-volatile or unstable. In either case, decompositionfrequently takes place giving rise to the formation of carbon and othersolid matter which deposits upon the vaporizing surface. This requiresintermittent shutdowns to clean the still.

This invention has for its object to provide improved vacuumdistillation process especially of the high vacuum mnobstructed pathtype. Other objects are to improve the state of the art. Other objectswill become apparent from the fol lowing description and claims.

These and other objects are accomplished by our invention which includesadding to the distilland which is to be subjected to vacuum distillationa substance which will increase absorption of radiant energy and thendispersing the distilland into a vacuum distillation chamber where it isheated substantially entirely by radiation to distillation temperature.

In the following description we have given several of the preferredembodiments of our invention, but it is to be understood that these areset forth for the purposes of illustration and not in limitationthereof.

In the accompanying drawing we have illustrated two preferred forms ofapparatus in which our invention can be carried out wherein like numbersrefer to like parts and wherein;

Fig. 1 is a vertical section of a high vacuum unobstructed path still inwhich the distilland is formed into a film or film-like spray byspraying it g o perature. Vapors evolved from the film pass to through aspray nozzle, into spaced relation with a radiant heater;

Pig. 2 illustrates a still similar to that of Fig.

1 but shows an alternative method of distributing the distilland in aself-supporting film by centrifugal force;

Fig. 3 is a vertical section of a satisfactory spray nozzle for theapparatus of Fig. l and Pig. 4 is a perspective view of the spray nozzledeflector tip.

Referring to Fig. l, numeral 4 indicates-a relatively flat circular baseplate supporting a hemlspherically shaped still casing or cover 8, whichis maintained in gas'tight relation with plate l by gasket 8. Numeral ldesignates a radiant heater which may be conveniently made of a scircular partition integral with base plate 4, and

numeral 2| designates a circular partition integral with plate 4 both ofwhich partitions cooperate to form a plurality of gutters 22 and 24.Numeral 2O designates a withdrawal conduit connected to gutter 22 andnumeral 2. designates a withdrawal conduit connected to gutter 24.Numeral lli designates an evacuating conduit which leads to a vacuumpump (not shown) Numeral 32 designates a broken line which is toindicate the path of travel oi the spray or film emitted from spraynozzle ll. I

Referring to Fig. 2, numeral 40 designates a shaft rotatably mounted ingas tight packing II, which is provided at the upper end with a 9driving pulley I! and at the lower end with a circular disk 44. Numeral4O designates a conduit passing through the wall of still casing i in agas tight manner, and terminating near the center of plate 44.

During operation of the apparatus illustrated in Fig. 1 liquid to bedistilled and containing a radiant heat absorbing material is passedunder pressure through conduit l2 and is sprayed 30 through spray nozzleH to form a self-supporting film having a conical shape. and indicatedby numeral 32. Radiant heater II is put into operation in order to heatthe film to distillation temperature and the still is evacuated throughconduit 30. The cone of distilland 32 is substantially entirelyself-supporting and does not materially come into contact with radiantheater ll. However, the heat from radiant heater is absorbed by the filmand is thus heated to distillation temthe casing 0 which is air cooledand are condensed thereon. These vapors then flow in the form of liquidcondensate into gutter 22 and are removed from the still by way ofconduit 26.

. Undistilled residue is thrown or collects in gutter 24 and iswithdrawn through conduit 28.

Spray nozzles are well known which will form .a self sustaining film orfilm of spray and these nozzles form no part of our invention. In Figs.

' 3 and 4 is illustrated a satisfactory nozzle which is on the market.It comprises a body member into one end of which is screwed the spraynozzle 82. Numeral N designates a hollow core in which is slidablymounted a deflector tip It.

56 Deflector ii is provided with slits l8 and nozzle ll with opening ll.Oil under pressure passes through the center of I, through slits ti andthence through 1|. Slits I. give a rotary motion to the oil whichpersists after passage through I. resulting in a liquid cone. The shapeof the cone can be changed by varying the pres-- sure of the oil flowingto the nozzle.

In operating the apparatus illustrated in Fig. 2 the still is evacuatedand the radiant heater is put into operation as described in connectionwith Hg. 1. Distilland which is heat absorbing or which contains heatabsorbing materials is introduced through conduit ll. Circular plate 04is caused to rotate at relatively high speed such as about 200 to 5000R. P. M. by force applied to pulley 42. The distilland flowing on to thecenter of plate 44 is caused to fiow to the periphery thereof bycentrifugal force, and is thenfiungasacurtainorfilmtothe wallof casing0. Heat is absorbed by the film from the radiant heater II and vaporsderived from the heated film condense on the upper part of casing I,fiow into gutter It, and are removed by way of conduit 20. Undistilledresidue is thrown to the lower wall of easing I and then flows by graviwinto gutter II and is withdrawn from the still by way of conduit it. Inorder to avoid heating of condensate in gutter 22 by the hot residuewhich impinges on the lower walls of easing C, a mass of insulatingmaterial 48 is maintained in contact with the base of gutter 22.

In order to increase the amount of radiant energy applied to the film,it is advantageous to utilize polished metal reflecting surfaces. Thesemay be located in the apparatus behind the radiant heaters so that theheat is radiated outward toward the film.

The self sustaining film or layer may be one continuous film of liquidor it may be composed of a body resembling a film in dimensions butcomposed of separate dropsof liquid.

Some distillands naturally absorb infrared wave lengths to aconsiderable extent, especially if a very thin film is not used. In suchcases addition of heat absorbing materials is not necessary. However,such materials may be added to the distilland even if they do exhibitinfrared absorption. A very satisfactory heat absorbent which may beadded is finely divided or colloidal carbon. Many distillands alreadycontain this material as a decompositibn product, in which case it neednot be added. Other materials such as powdered or colloidal metals ororganic dyes, which absorb infrared, such as colloidal iron, gold. etc.may be used. The absorbing materials should be sufficiently finelydivided that they will not interfere with the spraynozzle acilon or theaction of centrifugal force informing films. Also, they should not beadded in amounts sufiicient to interfere with this action even whenfinely divided. The amounts required will vary with the conditions ofdistillation and the materlal being distilled. They should be used inamounts sufficient to make the distilland substantially opaque to redand infrared. As 7 a general rule less than one per cent of heatabsorbing material will be found to be satisfactory. larger amounts suchas l to 10% are useful under special circumstances. Higher or loweramounts can be used and are to be understood as being within the scopeof our invention.

Contact of the film with the heater should be avoided as far aspossible. This can be done by placing the heater above the spray or bycareful adjustment of the spray and suitable spacing of the film fromthe heater. The same result is accomplished by admitting a small amountof air behind the heaters so that it passes in a direction from theheater to the film and thus prevents contact of the heater and film. Theair need only produce a forward stream of a few microns to accomplishthis result.

Our invention has the distinct advantage that no vaporizing surface isutilized and, therefore, periodic cleaning thereof is avoided. Aparticular advantage of the invention is that the distilland is heatedto distillation temperature while it is in a form such that rapidvaporization thereof can take place.

What we claim is:

1. The process of high vacuum unobstructed path distillation whichcomprises passing distiiland, in the formof a substantially continuous,physically unsupported film, between, and in spaced relation to, aradiant heater and a condensing surface which heater and surface areseparated from each other by substantially unobstructed space,evacuating the space between the radiant heater and the condensingsurface, heating the film of distilland to distillation temperaturesubstantially entirely by radiant heat from the radiant heater,condensing the vapors thus formed on the condensing surface and removingcondensate and unvaporized distilland from the evacuated space.

2. The process of high vacuum unobstructed path distillation whichcomprises adding a finely divided heat absorbing agent to thedistilland. passing this mixture of absorbing agent and distilland, inthe form of a substantially continuous, physically unsupported film,between, and in spaced relation to, a radiant heater and a condensingsurface which heater and surface are separated from each other bysubstantially unobstructed space, evacuating the space between theradiant heater and the condensing surface, heating the film ofdistilland to distillation temperature substantially entirely by radiantheat from the radiant heater, condensing the vapors thus formed on thecondensing surface and removing condensate and unvaporized distillandfrom the evacuated space.

3. The process of high vacuum unobstructed path distillation whichcomprises adding a heatabsorbing agent selected from the groupconsisting of finely divided carbon, finely divided, relativelynon-volatile organic dyes and colloidal metals to the distilland passingthis mixture of absorbing agent and distilland, in the form of asubstantially continuous, physically unsupported film, between, and inspaced relation to, a radiant heater and a condensing surface whichheater and surface are separated from each other by substantiallyunobstructed space, evacuating the space between the radiant heater andthe condensing surface, heating the film of distilland to distillationtemperature substantially entirely by radiant heat from the radiantheater, condensing the vapors thus formed on the condensing surface andremoving condensate and unvaporized distilland from the evacuated space.

KENNETH C. D. HICKMAN. JOHN C. HECKER.

